145
FXUS63 KGRR 280748 CCA
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
305 AM EDT FRI MAR 28 2025
KEY MESSAGES
- WARMER WITH SHOWERS AND CHANCE OF STORMS THROUGH SUNDAY
- RAIN TRANSITIONS TO SNOW AND DIMINISHES SUNDAY NIGHT INTO MONDAY
- ADDITIONAL PRECIPITATION MID-NEXT WEEK
DISCUSSION
ISSUED AT 304 AM EDT FRI MAR 28 2025
- WARMER WITH SHOWERS AND CHANCE OF STORMS THROUGH SUNDAY
ELEVATED SHOWERS AND THUNDERSTORMS ARE ON TRACK TO ARRIVE IN THE
COMING HOURS ASSOCIATED WITH A WARM FRONT SURGING NORTH ACROSS THE
STATE. CAPE LOOKS TO BE SUFFICIENT FOR GENERAL THUNDER, ON THE ORDER
OF A FEW HUNDRED JOULES, BUT NOT ANYTHING MORE THAN THAT. POOR MID-
LEVEL MOISTURE QUALITY WILL LIMIT WIDESPREAD PRECIPITATION TO UNDER
ONE-QUARTER INCH, THROUGH THE HREF LPMM SUGGESTS ISOLATED POCKETS UP
TO ONE-HALF INCH ARE POSSIBLE. BEST COVERAGE WILL BE ACROSS
SOUTHWEST LOWER MICHIGAN BECOMING MORE SPOTTY AS THE FRONT CROSSES
THE AREA GIVEN A DIMINISHED FRONTOGENETICAL RESPONSE. HIGHS WILL
RANGE FROM THE 50S NEAR US10 WHERE THE FRONT STALLS TO NEAR 70
ACROSS THE I94 CORRIDOR.
SATURDAY WILL INITIALLY FEATURE PRECIPITATION LIMITED TO THE
NORTHERN CWA NEAR THE FRONT, EXPANDING SOUTH THROUGH THE DAY AS THE
FRONT DRIFTS TO THE SOUTH. THERE WILL BE A NOTABLE TEMPERATURE
GRADIENT ACROSS LOWER MICHIGAN AS A RESULT OF THE FRONT. UNCERTAINTY
IS HIGHEST ACROSS THE NORTHERN CWA DUE TO HIGH DEPENDENCE ON
SPECIFIC FRONTAL POSITIONING. THE NORTHERN CWA IS FAVORED TO START
IN THE 50S, BUT FALL BACK INTO THE 40S/UPPER 30S BY EVENING. HIGHS
NEAR AND SOUTH OF I96 (WHICH IS APPROXIMATELY WHERE THE FRONT WILL
STALL SATURDAY NIGHT) ARE FAVORED TO REMAIN INTO THE 60S
SUNDAY, INCREASING SOUTHERLY FLOW DRIVES THE BAROCLINIC ZONE BACK TO
THE NORTH WITH 850MB TEMPS CLIMBING TO NEAR 10C. ACROSS SOUTHERN
MICHIGAN, TEMPERATURES WILL CLIMB WELL INTO THE 60S AGAIN. CENTRAL
MICHIGAN WILL BE MUCH MORE UNCERTAIN, REACHING THE FIFTIES IF THE
FRONTAL BOUNDARY MOVES NORTH OF THEM (FAVORED BY THE ECMWF/CMC
FAMILIES) OR STAYING IN THE THIRTIES IF IT STALLS ACROSS LOWER MI
(FAVORED BY THE GFS/NAM FAMILIES). THE GEFS HAS TRENDED SLIGHTLY
WARMER IN THE 00Z SUITE WHICH WOULD FAVOR MORE RAIN AND LESS OF AN
ICY MIX RISK. INSTABILITY ALSO RE-ENTERS THE PICTURE SUNDAY LEADING
TO A ATTENDANT THUNDER RISK WITH WIDESPREAD RAIN AS THE SURFACE LOW
APPROACHES. ONE THING WE WILL NEED TO WATCH IS THE POTENTIAL FOR A
FEW STRONGER STORMS ON SUNDAY. 30-45 KNOTS OF SHEAR WITH MUCAPE
VALUES LIKELY EXCEEDING 500-1000 J/KG MAY BE ENOUGH FOR SOME
ORGANIZATION OF STORMS, PARTICULARLY GIVEN BACKED WINDS ALONG THE
WARM FRONTAL BOUNDARY WHEREVER IT SETS UP.
- RAIN TRANSITIONS TO SNOW AND DIMINISHES SUNDAY NIGHT INTO MONDAY
AS THE SURFACE LOW DEPARTS SUNDAY NIGHT INTO MONDAY, COLD AIR
ADVECTION WILL TAKE HOLD LEADING TO RAIN MIXING WITH/CHANGING OVER
TO SNOW AS IT DIMINISHES. SOME UNCERTAINTY EXISTS IN HOW LONG
PRECIPITATION LINGERS GIVEN THE GFS SUITE FAVORS A QUICKLY DEPARTING
LOW, WHILE THE ECMWF AND CMC SUITES HOLD THE LOW AND ASSOCIATED
TROUGHING LONGER KEEPING PRECIPITATION INTO MONDAY. ACCUMULATION
CHANCES LOOK TO BE LOW, WITH AREAS NEAR AND NORTH OF US10 HAVING THE
BEST SHOT AT SEEING ANY ACCUMULATION. SURFACE AND UPPER-LEVEL
RIDGING THEN DRIES OUT THE AREA FOR TUESDAY.
- ADDITIONAL PRECIPITATION MID-NEXT WEEK
OUR NEXT SYSTEM ARRIVES WEDNESDAY AS A MID-LEVEL WAVE EJECTS A
SURFACE LOW THROUGH THE REGION ONCE AGAIN WITH HIGH CONFIDENCE IN
SOME FORM OF PRECIPITATION. ENSEMBLE CLUSTERS SUGGEST UNCERTAINTY IN
HOW THIS TROUGH INTERACTS WITH THE DOWNSTREAM RIDGING AFFECTING HOW
MUCH WARM AIR IS ADVECTED INTO LOWER MICHIGAN. IF WE END UP ON THE
COOLER END OF THE SYSTEM HIGHS TOWARDS THE 40S AND LIGHT SNOW OR A
RAIN/SNOW MIX ARE FAVORED. HOWEVER IF WARM AIR ADVECTION IS MORE
ROBUST HIGHS INTO THE SIXTIES AND RAIN ARE EXPECTED ONCE AGAIN.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 150 AM EDT FRI MAR 28 2025
VFR CIGS AROUND 5000 FT GIVING WAY TO MVFR TO IFR CIGS AND SHOWERS
TOWARD 12Z FRIDAY AS A WARM FRONT LIFTS NORTH TOWARD THE REGION.
A FEW TSTMS ARE POSSIBLE FRIDAY, WITH AN EMPHASIS ON ROUGHLY
14Z-19Z AS THE WARM FRONT IS OVERHEAD/PASSING THROUGH.
SHOWERS ENDING AND CONDITIONS TURNING VFR WITH THE PASSAGE OF THE
WARM FRONT TO THE NORTH AFTER 18-19Z. WINDS INCREASING OUT OF THE
SOUTH TO 15 TO 25 KTS AS WELL. STRONG LOW LEVEL JET OF 50-55 KTS
WILL BE OVERHEAD ON FRIDAY EVENING IN THE SYSTEM WARM SECTOR, SO
THE THREAT FOR LLWS WILL INCREASE BY 00Z SAT.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 11 AM EDT
SATURDAY FOR LMZ844>849.
DISCUSSION...THOMAS
AVIATION...MEADE
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